1. Field of the Invention
This invention relates to improvements in control systems for automatic guided vehicles of the type having vehicle controllers on board the vehicles, traffic controllers remote from the vehicles for transmitting control information to the vehicles, and administration controllers for processing vehicle movement requests and transmitting the processed requests to the traffic controller.
2. Discussion of Related Art
Automatically controlled vehicles are becoming more common in applications such as warehousing facilities for storing and retrieving goods, manufacturing facilities for supplying raw goods to processing stations and removing finished goods from processing stations, and facilities for moving passengers from point to point. Such systems can become quite complex and require a high sophistication in control technique in order to most efficiently use available computer resources. To date, there have been many types of control systems suggested for automatic guided vehicles.
U.S. Pat. No. 4,015,804 shows one example of a control for guided vehicles having a system management center which receives control commands and line assignments of vehicles taken into and out of service. The system management center sends directions to a vehicle control center. These directions include instructions as to vehicle number, switch direction, destination, optimum speed, coupling commands, etc. These instruction are then communicated to the vehicles through a vehicle control center which receives information back from each vehicle regarding its status, position, velocity, etc.
U.S. Pat. No. 4,333,147 shows a multiplex automated guidance system for controlling moving vehicles along a plurality of partially coincident travel paths defined by an equal number of guideway conductors.
U.S. Pat. No. 4,530,056 discloses an automated guided vehicle system in which vehicles follow a guide path defined by wires carrying electrical signals with selective routing between stations along the path.
U.S. Pat. No. 4,278,142 discloses a system for the automatic guidance of a vehicle along a scheduled road route, which comprises marks of varying shapes possessing respectively specific travel function information and attached to the surface of the roads selected for the vehicle's travel.
U.S. Pat. No. 4,630,126 discloses a computer control conveying system provided for use in transporting materials between locations.
A conventional automated guided system is sold by Portec Inc., Automated Systems Division, 4500 Western Avenue, Lisle Illinois. This system is sold under the designation "Portec Navigator" and includes a plurality of guided vehicles each of which has an on board vehicle controller which includes a microprocessor, a timer, a speed controller, an input/output subsystem, and a full duplex on-board data transmitter. The vehicle controllers communicate with a traffic controller which communicates task assignments and blocking instructions to vehicles, optimizes task assignments, usually on a first in/first out basis, interfaces with ancillary input/out systems of a load sensor and remote terminals, and controls accessory equipment such as doors, elevators and safety devices. The traffic controller is based around a minicomputer and runs on software programs based on standard modules. The traffic controller interfaces with the administration controller which incorporates diagnostic and data reporting programs and performs other types of functions.